Lager fermentation - Diacetyl rest?

[Swift Pint]

I've got two lagers on the go at the moment, an Oktoberfest and a Doppelbock, both have been in the fermentor for 10 days now, both with WLP833 German Bock yeast.

I pitched cold for both of them, about 6c, letting the temp slowly rise over a couple of days to 9c, where it has remained (give or take).

I'm wondering if I need to do a diacetyl rest. I think I'm at the stage where I would start raising the temperature if I was going to do one.
I've read THIS, and the graphs seem to suggest that as long as the yeast are still active when I start lagering, then diacetyl won't be a problem. I think I've got fairly good control over my temperatures so I think I could cool it down to lagering without shocking the yeast.

If it don't do a diacetyl rest but end up with diacetyl am I screwed or can I fix it later? :wha:
I've only brewed 1 lager before, so am not really familiar with whether a diacetyl rest is necessary, or something that is done out of unnecessary paranoia?

 

[calumscott]

:hmm: I was under the impression you just ferment them close to the intended FG then bring them into the warm for a couple of days then chill them down for lagering...

that all looks *very* technical.

 

[Jimmy321]

I'm no expert but I read up about it before making an October Fest style in January and when it had got through 2/3 of fermentation I brought it up to 20°C to finish off. The main reason I decided to do this was under pitching of yeast.

It was lagering in my garage during the cold snap and transferred to my fridge and is now tasting really good.

 

[BrewByBrandis]

The graphs you see (is it F youre thinking of mainly?) is only if you do kraeusen (adding same or fresch wort at the end of the fermentation)
I recomend you to do a diacetyl rest after 75% of the fermentation is done , or if your est FG is around 1.010 do it around 1.020-1.025, for at least 2 days and then cold lager before bottling/kegging
This method helped me to get rid of diacetyl in my lagers.
If you get a butterscotch taste in your brews after aprox 3 months in bottle/keg, long lagering MIGHT help, but dont count on it.

 

[Swift Pint]

OK, sounds like its definitely worth doing :thumb:
I'll take a gravity reading tonight and think about ramping the temps up.

Thanks for the advice guys.

 

[Swift Pint]

umm, quick question, does it matter how fast I ramp up the temp? Should I do it slowly or just turn off my cooling and let it free rise?

 

[DirtyCaner]

I raise temp from fermentation temp to diacetyl rest temp by 1C a day until rest temp reached.

 

[rpt]

I raise temp from fermentation temp to diacetyl rest temp by 1C a day until rest temp reached.

Does it need to be that slow? If you ferment at 12C and rest at 20C then that's over a week.

 

[DirtyCaner]

I rest at 16 for 2 days. So it takes about a week to raise temp and rest.

I don't know if it has to be that slow, that's just what I do, never tried it nay other way. The results have been good so far though.

 

[rpt]

I've only done one lager (an extract kit using Saflager yeast) and I didn't do a diacetyl rest, but it tastes fantastic. The first 24 hours were fermented at 20C then it was at 12C until finished followed by lagering for 2 weeks at 2C.

 

[Good Ed]

I've used WLP833 four times and haven't done a diacetyl rest with any. If you ferment cool with this yeast, and pitch enough of it, you won't have any problems with diacetyl. I just follow Jamil's advice and pitch cool let it come up to about 10c and just forget about it for three weeks by which time you will be at FG.